Motor systems 2 - cerebellum Flashcards
(12 cards)
Briefly outline the function of the cerebellum
- regulation of posture indirectly by adjusting output of major descending motor pathways
- acts as a comparator correcting discrepancies between intended and actual movements
- can act as a timer sequencing motor activation
- role in motor memory
- instigates ‘learned’ motor sequences
Damage to the spino-cerebellum can…
result in hypotonia (reduced muscle tone)
- ataxia (unsteady staggering gait)
- dysmetria (inaccurate termination of movement )
- intention tremors
Damage to the Vestibulo-cerebellum can…
result in slow saccades (fast tracking ocular movement)
- Nystagmus
- Ataxia
Damage to the Cerebro- (ponto) cerebellum can..
lead to Dysmetria intention tremor
- Asynergy (uncoordinated agonist and antagonist muscles)
- Dysarthria inarticulate speech
Summarise the direct inputs to the cerebellum
climbing fibres- input from the inferior olive
-excite Purkinje cells
The indirect inputs ….
Mossy fibres from brainstem nuclei, indirectly excite Purkinje cells via parallel fibres of granule cells
outputs from the cerebellum include
ONLY via Purkinje cells, these project deep into the cerebellar nuclei and send inhibitory signals.
The DCN
can compare two different inputs
- direct inputs from mossy fibres/ climbing afferent collaterals BEFORE
- AFTER cerebellar processing has occurred via inhibitory P cell input
- error signals
the stored motor plan..
compares what should of happened with what actually happens
the efference
is direct sensory input from MF/ CF into the DCN
- actual movements
the afference
is indirect input into the DCN via the P cell after cerebellar processing has occurred
- intended movements
error signal
ensures matching between intended and actual movements via indirect Purkinje innervation of the DCN
